Coin-operated devices occupy a prominent role in fulfilling consumer needs in today's society. In order for such devices to be effective, however, they must be fully operational, which is to say that they contain an adequate supply of products, that they can accept payment for its products, and that they are capable of delivering products. In particular, the telephone industry maintains an extensive network of coin-operated telephones, so prompt and efficient collection and maintenance visits are important factors in the overall profitability of its network. For example, there is unnecessary waste in dispatching a person to collect a partially filled collection box. In the past, attempts to predict optimum collection schedules were based, to a large extent, on extrapolations of previous records. This problem was solved by having each coin-operated device periodically communicate its status to a reporting station so that it could be properly maintained.
U.S. Pat. No. 4,124,774 discloses a Telephone Station Coin Memory and Control System wherein each time a call is made from a payphone, circuitry within the local switching office which serves the payphone interrogates the memory of the payphone to obtain information regarding the precise number and type of coins deposited since the last collection in order to measure coin box fill. The local switching office is sometimes known as the Telephone Company Central Office. Frequency shift keyed (FSK) signals are used to transmit this information to the Central Office which is equipped with a coin processor and centralized coin information storage for a plurality of payphone stations. Although this technique is useful when a dedicated link exists between the payphone and the reporting station (e.g., the Central Office), private payphones are not maintained by the telephone company. Consequently, individual telephone calls must be made between the payphone and its reporting station. Unfortunately, in a large network of coin-operated devices, many of the calls are not local and require payment.
Polling is a well-known procedure in which the reporting station itself initiates a telephone call to each payphone in order to check the operational status of the payphone and to download information, such as new charging rates, into its memory. This procedure is somewhat unsatisfactory due to the number of toll telephone calls that must be made only to learn that all is well. Unfortunately, increasing the time interval between polling calls leads to a corresponding increase in the number of payphones that are out of service. One solution to this dilemma is to have the payphone call the reporting station only when maintenance is required. U.S. Pat. No. 4,599,492 discloses such a system in which each payphone, in a group thereof, includes circuitry for dialing a predetermined telephone number during a maintenance condition. While such a technique has advantages, a large number of toll calls are still required--not only by the payphone, but also by the reporting station to verify that the payphone is capable of making an outgoing call.
Even in the most streamlined networks where the coin-operated devices (Slave stations) report to local data collection sites (Master stations) so that only one toll call from each local area needs to be made, there are still deficiencies. For example: special equipment is normally required at the Master station, changing the locations of Master stations is occasionally necessary, changes in local and long distance calling rates preclude any one network structure from being optimum for long, and adding new coin-operated devices to the network leads to a different optimum network configuration. In short, it is highly desirable to be able to reconfigure a network of coin-operated-type devices with minimum cost and inconvenience.